Multiple human pressures and their spatial patterns in European running waters

Abstract

Running water ecosystems of Europe are affected by various human pressures. However, little is known about the prevalence, spatial patterns, interactions with natural environment and co-occurrence of pressures. This study represents the first high-resolution data analysis of human pressures at the European scale, where important pressure criteria for 9330 sampling sites in 14 European countries were analysed. We identified 15 criteria describing major anthropogenic degradation and combined these into a global pressure index by taking additive effects of multiple pressures into account. Rivers are affected by alterations of water quality (59%), hydrology (41%) and morphology (38%). Connectivity is disrupted at the catchment level in 85% and 35% at the river segment level. Approximately 31% of all sites are affected by one, 29% by two, 28% by three and 12% by four pressure groups; only 21% are unaffected. In total, 47% of the sites are multi-impacted. Approximately 90% of lowland rivers are impacted by a combination of all four pressure groups.

Restoration in Integrated River Basin Management

“…Ongoing challenges to successful restoration are currently demonstrated by the persistence of large-scale impacts, e.g., extensive areas of intensive land use in the catchment or numerous migration barriers (weirs, impoundments, ramps) limiting the recolonization through interrupted longitudinal connectivity. Moreover, current fluvial systems are confronted with multiple pressures that cannot be solved solely by morphological habitat restoration (Schinegger et al 2012;Tockner et al 2010;Hering et al 2015). This calls for further improvements to an integrative and basin-wide approach that goes beyond fluvial morphology to account for all functional aspects of river systems.…”

“…There are relatively few ambitious restoration programs that address all the multiple pressures that are typical for the majority of alpine river landscapes, e.g., altered flow and sediment regimes (Schinegger et al 2012;Muhar et al 2013). …”

Land Use

“…The synergistic and antagonistic effects of multiple pressures are still not fully untangled (Schinegger et al 2012) despite much ongoing research (e.g., Nõges et al 2016;Piggott et al 2015;Schinegger et al 2016). As many catchments face pressures related to more than one land use category (e.g., agricultural and urban land) as well as multiple human pressures, it is essential to understand in detail the different impact pathways and the interrelationships between the different pressures to develop robust management strategies.…”

Fish-based groups for ecological assessment in rivers: the importance of environmental drivers on taxonomic and functional traits of fish assemblages

“…Overall, river-types with higher human density tend to present higher degradation conditions and therefore reference sites can be quite rare (Matono, 2012). The least disturbed river-types are usually located in high altitude regions (and small drainage basins), frequently in isolated areas with difficult human access, far from the main human pathways (Chaves et al, 2006;Schinegger et al, 2011). The WFD defined abiotic descriptors for classifying streams and rivers into types (Annex II, Section 1 of the WFD) according to two alternative systems: (i) "system A", the fixed typology, is defined by ecoregions (according to Illies, 1978), based on the catchment area, catchment geology and altitude; (ii) "system B" uses five obligatory factors (latitude, longitude, altitude, geology and drainage area of the basin), and an additional group of optional factors.…”

“…In Europe, about 80% of rivers are affected by water pollution, water removal for hydropower and irrigation, structural alterations and the impact of dams (Schinegger et al, 2011). Over the last few decades tremendous efforts have been undertaken to develop management strategies to improve the ecological status of these ecosystems.…”